Fuel lift carburetor



Patented Mar. 10, 1942 FUEL um' canauaa'ron `Harold W. Meade, Covington,Ind, applic-uan september 11, 193s, serai No. 101,214

(ci. s-sei) 11 Claims.

My invention relates primarily to fuel-feed systems for internalcombustion engines usmg liquid fuel and has for its object the provisionof a fuel-feed system which will elevate fuel from a supply tank to thepoint of delivery anu which will be simple in construction and positivein operation. Another object of my invention is to produce a fuel-feedsystem which can readily be embodied in association with a carburetor ofany desired type. A further object ofv my invention is to provide asuction-operated fuel-feed system of an automobile with meansforpreventing flooding should the automobile ever asume a position inwhich fuel would tend to ow by gravity from the supply tank.

Still another object of my invention is to provide for asuction-operated fuel-feed system, or for any other suction-operateddevice, means which will insure the existence of a minimumpressure-differential under varying conditions of engine operation.

The accompanying drawingsv illustrate my in-A closed when the fuel-levelin the chamber I3 is at or above a predetermined point. Y

Fuel is supplied to the chamber I3 through a port 2| communicating withthe fuel-supply line 22 leading from a supply tank 20 which normally isat a lower level than the chamber I3. The

bottom of the chamber I3 is provided with a fuel-discharge opening 23 bymeans of which the fuel in the chamber may flow into the reservoir lll;and associated with the opening 23 is ava-Ive member 24 connected tomove with the diaphragm I4.

Also movable with the diaphragm I4, and conveniently mounted directlyupon it, is an upwardly opening cup-shaped member 25 which receives astationary piston 26 and a spring 21, the latter acting between thepiston 26 and the bottom of the cup to exert a downward force on thediaphragmV I4. A' small port 28 'extending through the bottom of the cupprovides communication between the interior thereof and that portion ofthe chamber I3 lying beneath vention: Fig. 1 isalsomewhat diagrammaticview of a carburetor and associated fuel-feeding sys-V and Fig.- 3 is afragmental view similar to Fig. 1 f

but showing the movable parts of the device in different positions.

The carburetor shown in the drawings embodies a fuel reservoir .I0which, in that fuel supplied at regulated rate from it passes through ajet II to the mixture intake conduit I2 of the engine, is the equivalentof the float-bowl in the conventional carburetor; .but the reservoir I0diii'ers from the conventional float-bowl in that it embodies no float.Associated with the reservoir l0, and conveniently disposed therein, isa fuel-feeding chamber I3 divided horizontally by a exible diaphragm I4.That part of the chamber `I3 lying above the diaphragm I4 communicatesthrough a port I5 with a conduit I6 by means of which it is subjected tosubatmospieric 'pressure as the result, either directly or indirectly,of the partial vacuum existing Within the intake manifold of the enginewhen it is operated.

That portion of the chamber I3 lying below the diaphragm I4 alsocommunicates, through a port I1, with the conduit I6; but associatedwith the port I'I there is a valve IIi controlled 'by a float I9 -in thechamber and sc arranged as to be the diaphragm. vIn the annular wall ofthe cup 25 there of are one or more .ports 29 which providecommunication between the interior of the cup and that portionof thechamber I3 lying above the diaphragm, the ports 29 being so located thatin upward and downward movement of the cup and diaphragm they arealternately covered and uncovered by the lpiston 26.v

Conveniently, the upper end of the chamber I3 is so formed as to receivethe .upper end of the cup 25 and to serve as a guide therefor. The valve24 may be connected to the diaphragm by a valve stem 30, the upper endof which is screw-threaded into the bottom of the cup 25. 'Ihis valvestem 30 may conveniently serve as a guide for the float I9.

Except for the air-discharge ports I5 and I'I, and the fuel inlet anddischarge openings 2| and 23, the chamber I3 is sealed. Thefuel-reservoir IIL, however, is open to atmosphere as through a port 32near the top thereof.

The parts of the device are illustrated in Fig. 1 `of the drawings inthe positions they respectively occupy when the fuel contained in thechamber I3 is being discharged into the reservoir I0 and is not beingaugmented by any fuel supplied through the port 2|. Under suchconditions, the valve I8 is closed by the float I9 and the diaphragm II, under the inuence of intakemanifold vacuum available through theconduit I6, is elevated to maintain the valve 24 open and the ports 29closed. Under these circumstances,

the fuel-level in the reservoir II) remains approximately constant at anelevation just sufficient to prevent air flow from the reservoir ID tothe chamber I3, for fuel can not escape from the chamber I3 except asair enters the opening 23 to permit its displacement. As fuel is usedfrom 5 the reservoir I0, the opening 23 is uncovered, and air enters thechamberV I3 through the opening 23 to permit fuel to run'into thereservoir I0,

When the fuel level in the chamber i3 drops to the point where the valve'I 8 opens, as .indicated l0 in Fig. 3, vthe sub-atmospheric pressureofthe intake-manifold is applied through the tube IE to the chamber I3below the diaphragm I4 to counteract the effect on the diaphragm I4 ofthe subatmospheric pressure existing thereabove.

prevent any further discharge of fuel through the opening 23. Because ofthe sub-atmospheric pressure now existing in the chamber I3 as theresult of the opening of the valve I8 fuel from the tank 20 is drawnthereinto through the pipe 22 and port 2 I. The tank 20, of course, isvented.

As fuel enters the chamber I3' the fuel-level 25 differential pressuretending to elevate the diaphragm is created. Two factors contribute tothe creation of such a differential pressure. In the first place, theliquid fuel cannot enter the port 28 with the same facility as did air;and, in

the second place, any liquid fuel which does enter the port and the vcup25 builds up a liquid column rising above the level ofthe fuel below thediaphragm and creating a hydrostatic pressure which, transmitted to thelower surface of the diaphragm, tends to move it upwardly. As the resultof these factors, the diaphragm I4` is raised to open the valve 24 andclosethe ports 29, as shown in Fig. 1. The closing of the ports 29preventsy the imposition of sub-atmospheric pressure upon the fuel inthe chamber 83 even 50 .when the fuel-level therein drops; and fuel istherefore free to escape from vthe chamber I3 into the reservoir Illasair enters the opening 23. I have found it desirable to associate withthe opening. 23 a" downwardly extending tube Q0, the 55 lower end ofwhich is cut off obliquely at a relatively sharp angle. In the absenceof such or an equivalent arrangement I find that the opening 23 must bemade inordinately large; as otherwise the surface tension of the liquidfuel may .pre- 60 vent it from running out of the chamber I3 even whenthe level in the reservoir I9 drops below the bottom of the chamber.

During the interval in which lthe valve 24 is closed, the fuel level inthe reservoir I0 will drop 5 as fuel is discharged into the mixtureconduit, and will continue to drop until the chamber I3 becomes filledwith fuel. In practice, I have found no vdifficulty in so proportioningthe device that the chamber la will remi before the fue1 .m

level in the reservoir I0 has dropped vsufdciently to effect anymaterial change in the mixture proportions.

Y In the ordinary operation of an automobile As l5 the result of thiscounteracting effect and of the force exerted by the spring 21, thediaphragm is forced downwardly to close the valve 24 and to pressureapplied 30 low speed and open throttle, when the intake manifold vacuumis insufficient to be depended upon to elevate the fuel into the chamberI3. I therefore prefer to employsome type of booster arrangement bywhich the effect of intake-manifold vacuum in creating sub-atmosphericpres sure in the chamber I3 may be augmented. To this end, I may disposebetween the carburetorthrottle 45 and the engine a venturi 46 the throatof which communicates through ports 4l with an air-inlet passage 48supplied with air through the venturi 49 of an aspirator 50. The throati of this aspirator communicates with the tube I6;

and, as the static pressure at the throat of the aspirator venturi 49will be lower than that at the throat of the venturi 46, which latterpressure will in turn be lower than that existing' in the intakemanifold beyond the venturi 45, the pressure applied through the tube I6to either the upper or both compartments of the chamber I3 will be;materially lower than that existing in the intake manifold. With thisarrangement, fuel can be elevated through a considerably lgreaterdistance than if the unaided intake-manifold vacuum were employed.

Even when the booster effect of such a device as the aspirator 50 isutilized, there still may be occasions when the intake-manifold vacuumis insufficient to elevate fuel into the chamber I3. To prevent thiscondition from interfering with the satisfactory operation of my deviceI may include therein mechanism which will in- 'sure that a.predetermined lminimum vacuum will exist in the intake-manifold. Asindicated in the drawings, this mechanism takes the form of apressure-responsive element which `controls the position of an auxiliarythrottle valve 56 disposed in the intake yconduit ofthe engine betweenthe throttle 45 and the venturi 46, the arrangement being such that adecreased vacuum -in the intake-manifold will result in a partialclosing of the auxiliary throttle 56.

Preferably, the pressure-responsive element 55 is responsive, notdirectly to the pressure in the intake manifold, but instead to thepressure at the throat of the aspirator-venturi 49. As the s vacuum atthe throatl of the aspirator 49 is usually several times as great asthevacuum` in the intakemanifjold, I am thus enabled to use a lesssensitive pressure-responsive mechanism in the element 55,., 1

As indicated in the drawings, the pressureresponsive element 55 includesa casing 5l within which is mounted a diaphragm 58 dividing the interiorof the casing into two compartments, the upper one of which communicateswith Athe throat of the venturi 49 and the lower of which communicateswith the atmosphere. 59 tends to force downwardly the diaphragmy 58 anda slidable member 6 0 which is rigid therewith and which projectsoutwardly through the lower wall of the casing 51. The lower end of thesliding member 50 is connected, as by means of a link 5I, with an arm 62on the shaft of the auxiliary throttle 56.

Any drop in intake-manifold vacuum will be reflected as an increasedpressure at the throat of the venturi 49; and this increased pressure,aided bythe spring 59, will force downwardly the .diaphragm 58 andmember 50 to move the auxiliary throttle Valve 56 toward closedlposition.J This vmovement of the throttle valve will impose aArestriction upon the gases flowing through the intake conduit and willthus create engine conditions frequently arise. especially at apressure-drop (or an increase in vacuum) in A spring theintake-manifold. When the vacuum in the intake-manifold is above thepredetermined minimum, the resultant reduced pressure at the throat ofthe venturi 49 will-be transmitted to the upper compartment on thecasing 51 with the result that the diaphragm and slidable member 60 willbe raised and the valve 56 moved toward open position so as to reducethe resistance it offers to the yflow of mixture through the intakeconduit.

The auxiliary throttle '56 with its operating mechanism has Vanadvantage in addition to its function of maintaining a minimumintake-manifold vacuum as such. When an internal combustion engine isoperating at low speeds and fully open throttle the velocity of flow atall points along the intake conduit is not infrequently so low that pooratomization of the liquid fuel is obtained. As a result, the engine maydeliver less power than if the throttle were partially closed or theintake-conduit otherwise restricted` to produce a localized increase inthe velocity of mixture-flow. My auxiliary throttle 56 operatesautomatically to produce such a lo. calized increase in mixturevelocitypfor the drop in intake-manifold vacuum which occurs at lowspeedsand open throttle causes the .pressureresponsive element 55 tomove the auxiliary throttle 56 toward closed position and increase thevelocity of the mixture flowing past it.

With my invention embodied in an automobile conditions may arise, aswhen the automobile with its gasoline tank'i'n the rear and engine infront is headed down a steep slope, under which' the chamber I3 may belower than the fuel tank. In these circumstances, `fuel would tend toflow by gravity from the fuel tank into thechamber I3. To prevent this,I may place in the fuel-supply line 22 a valve 65 controlled by apressure-responsive element 66' responsive to the pressure in thechamber I3 and adapted to close the valve 65 whenever the pressure inthe chamber I3 becomes substantially atmospheric. So long as the chamberI3 is not full, fuel can of course iiow thereinto without producing anyharmful result; and as soon as the chamber I3 becomes full, itsconnection with the Athroat of the venturi 49,(or with theintakemanifold) is broken to destroy the partial vacuum which previouslyexisted. When this occurs, the pressure-responsive element 66 closes thevalve 65 and prevents fuel from running into the chamber I3 even if thefuel-supply tank is above the level of the chamber I3. Y I claim as myinvention: 1. In a fuel feed apparatus, a fuel reservoir, a

fuel feed chamber disposed above said reservoir in said chamber andcontrolling the connection.

between said air-exhausting means and said lower compartment, a fueltank below said chamber and .connected to the lower compartment thereof,said fuel tank being open to atmosphere,A

means providing a passage between said upper vand lower compartments,said passage being restricted to Yan extent such that upward fuel-owthrough it under the influence of said exhausting means cannot occurwithout the existence of valve in said passage and operativelyassociated a differential pressure sufficient to""`raise said diaphragm,and gl-provlsions for preventing flow through said passage when 'saiddiaphragm.A is

raised. i

2. In a fuel-feed system, a fuel-feed chamber,

a horizontal exible diaphragm dividing said chamber into upper landlower compartments and biased downwardly, a fuel-supply tank connectedto said lower compartment, said fuel tank being open to atmosphere,means forG exhausting said upper compartment, means providing a passagebetween said upper and lower compartments, a

operatively Connected to said diaphragm to be opened when the diaphragmis raised.

3. In a fuel-feed system, a fuel-feed chamber, a Vfuel-supply tank opento atmosphere and connected to said fuel-feed chamber, an air chamberadapted' for connection to air-exhausting means, means providing apassage connecting said two chambers and -communicating with saidfuel-feed chamber at a point slightly below the maximum fuel leveltherein whereby fuel will enter the passage as such maximum fuel levelis approached, a valve in said passage, a pressureresponsive elementresponsive to the differential in fluid pressures at opposite ends ofsaid passageand operatively associated with said valve, said yfuel-feedchamber being provided with an outlet port near itscbottom, an outletvalve controlling said outlet port and operatively connected to saidpressure-responsive element to be closed thereby in response to theeffect of differential pressures thereon, said passage being restrictedto an extent suchthat fuel-flow through it cannot occur withoutthe'creation of a pressure-differential sufficient to cause saidpressureresponsive element to close said first named valve.

4. In a fuel-feed system, a fuel-feed chamber, a fuel-supply tank opento atmosphere and connected to said fuel-feed chamber, an air chamberadapted for connection to air-exhausting means, means providing apassage connecting said two chambers, a valve in said passage, saidfuel-feed chamber being provided with an outlet port near its bottom, anoutlet valve controlling said port, and means operative when the fuellevel in said chamber reaches a predetermined maximum for closing saidfrstnamed valve and opening said outlet valve, said means including apressure-responsive element responsive to the differential influidpressures at opposite ends of said passage and operating both saidvalves.

l5. In a fuel-feed system, a fuel-feed chamber, a Yhorizontal Iflexible,diaphragm dividing said chamber into upper and lower compartments, afuel-supply tank below said chamber and connected 'to the lowercompartment thereof, means for exhausting said upper compartment, meansproviding a restricted passage between said upper and lowercompartments, said diaphragm being biased downwardly with a forcegreater than the resultant of the'total fluid pressures on oppositesides of said diaphragm when air is flowing upwardly through saidpassage under the influence of saidI exhausting means and less thansuchresultant when liquid fuel is flowing upwardly through said passageunder the influence of said exhausting means, said lower compartmentbeing provided with an outlet near its bottom, an outlet valvecontrolling said outlet, and a second valve controlling ow through saidrestricted passage, said diaphragm being operatively connected to saidvalves to close the latter and openthe former when the diaphragm movesupwardly as the result of the entry of'liquid fuel into said passage.

6. 'In a fuel-feed system for an internal combustion engine having anintake passage, a fuel- Asaid valve and thereby preventing egress offuel through said outlet and means for intermittently connecting saidfuel chamber to said intake passage to exhaust said chamber and inducefuelflow from said supply tank to said chamber, said means including apressure-responsive element responsive at all times to uid pressure insaid passage -and operative upon the conclusion of each period ofchamber-exhaustion to open said valve. against the iniiuence of saidyieldable means and to maintain it open until the chamber issubstantially empty of fuel or until the pressure in said passagereaches a predetermined maximum.

'1. In a. fuel-feed system`- a fuel reservoir, a fuel-feed chamberdisposed above said reservoir and having near its bottom an outlet portthrough which fuel may pass to said reservoir, a fuel supply tank, aconduit interconnecting said supply tank and said fuel-feed chamber,means for intermittently exhausting said fuel-feed chamber to inducefuel flow thereinto through said conduit, an outlet valve controllingsaid outlet port, mechanism for automatically closing said valve duringperiods in which said fuel-feed chamber is maintaining said last namedvalve closed when the fluid pressure in said chamber is above apredetermined value and open when such pressure is below thatpredetermined value.

8. In a fuel-feed system, a fuel reservoir, a

of fuel from said chamber into said reservoir; a valve in said conduit,and means for automatically opening saidlast named Ivalve when saidoutlet valve is closed and for closing said last named valve whensaid'outlet valve is open.

9. In a fuel-feed system, a fuel-feed chamber,

- a fuel supply tank disposed below said fuel-feed chamber, afuel-supply conduit interconnecting ,said fuel-feed chamber and supplytank, said fuel-feed chamber having an outlet port near its bottom, anoutlet valve controllingfuel iiow through said port, an air chamber,means providing a passage between said two chambers, said passagecommunicating with said fuel-feed chamber at a point adjacent but belowthe maximum fuel level therein, a second valve in said passage,air-exhausting means connected to said two chambers, means responsive tothe differen- .tial in fluid pressures at the respective ends of saidpassage and operatively connected to said outlet valve and said secondvalve, said passage being restricted to an extent such that fuel flowthrough it from said fuel-feed chamber into said air chamber cannotoccur without the existence of a pressure-differential sufiicient tocause said pressure-responsive element to close said. second valve, athird valve controlling the connection of said air-exhausting means tosaid fuel chamber independently of said second valve, means responsiveto fuel-level in said fuel-feed chamber for opening said third valveWhenever the fuel level in said fuel-feed chamber reaches apredetermined minimum, a fourth valve in said fuel-supply conduit, andmeans responsive to fluid-pressure in said fuel-feed chamber formaintaining said fourth valve closed except when the uid pressure insaid fuel-feed chamber is at or below a vpredetermined maximum.

10. In a fuel-feed apparatus, a fuel-feed chamber, a fuel-supply tankbelow said chamber and outlet port near its bottom, an outlet valvecontrolling said port, an air chamber, an air-exhausting means connectedto said air chamber, said two chambers being interconnected by a passagethrough which air may be exhausted from said fuel-feed chamber to inducefuel-flow thereinto from said supply tank, a second valve in fuel-feedchamber'disposed above said reservoir and having near its bottom anoutlet port through which fuel may pass to said reservoir', a fuelsupply tank, a conduit interconnecting said supply tank and saidfuel-feed chamber, means for intermittently exhausting said fuel-feed`chamber to induce fuel' flow thereinto through said conduit, an outletvalve controlling said outlet port, mechanism for automatically closingsaid valve during periods in which said fuel-feed chamber is beingexhausted and for opening said valve during the intervals between suchexhaustion periods, said outlet' port constituting the sole passagefor'the admission of air to said fuel-feed chamber whereby-to provide abarometric feed said passage, means responsive to the fuel-level in saidfuel-feed chamber for automatically closing said second valve when suchfuel-level rises to a predetermined maximum, said means including apressure-responsive element jointly responsive to the respectivefluid-pressures in said two chambers and operating to close said secondvalve whenever the fluid pressure in said air chamber is below that invsaid fuel-feed chamber and to open said second valve when the fluidpressures in said two chambers are substantially the same, and asecondmeans responsive to fuellevel in said fuel-feed chamber andoperating when such fuel-level reaches a predetermined minimum toequalize the pressures in said two chambers and thereby cause saidpressure-responsive element to open said second valve.

' ll. The invention set forth in claim 10 with and to be closed therebywhen said secondvalve is opened. Y y

HAROLD W. MEADE.

